Method for separating uranium and/or thorium

Abstract

The invention pertains to a method for separating uranium and/or thorium from an aqueous suspension, said method comprising: a) Contacting said suspension with at least a polymer having formula (I), wherein n is an integer which is not 0 and is no more than 50, R1 is H or CH 3 , R2 is H or a C1-C20-alkyl, R3 and R4 arc independently H or a C1-C20-alkyl, X, Y arc O or NH, said polymer being soluble in said aqueous suspension, and wherein when R3 and R4 are H, p is an integer which is 1 or more and 10 at the most, and said polymer is a flocculating polymer, and when at least one of R3 and R4 is not H, p is an integer which is 3 or more and 10 at the most, and said polymer is a thermosensitive polymer and has a LCST in said suspension, b) Carrying out at least one of the following steps b1) and b2) b1) If said suspension contains uranium, separating the aggregates resulting from flocculation of said polymer, from said mixture, b2) If said suspension contains thorium, modifying the mixture until the LCST of the polymer in the mixture is reached or exceeded and separating the resulting aggregates from said mixture; and c) Recovering at least one of uranium and/or thorium-free mixture, aggregates bearing uranium and aggregates bearing thorium.

1 . A method for separating uranium and/or thorium from an aqueous suspension, said method comprising:
 a) Contacting said suspension with at least a polymer having formula (I)   
       
         
           
           
               
               
           
         
         wherein 
         n is an integer which is not 0 and is no more than 50 
         R1 is H or CH 3 , 
         R2 is H or a C1-C20-alkyl, 
         R3 and R4 are independently H or a C1-C20-alkyl, 
         X is O or NH, 
         Y is O or NH, 
         said polymer being soluble in said aqueous suspension, and 
         wherein 
         when R3 and R4 are H, p is an integer which is 1 or more and 10 at the most, and said polymer is a flocculating polymer, and 
         when at least one of R3 and R4 is not H, p is an integer which is 3 or more and 10 at the most, and said polymer is a thermosensitive polymer and has a LCST in said suspension, 
         b) Carrying out at least one of the following steps b1) and b2) 
         b1) If said suspension contains uranium, separating the aggregates resulting from flocculation of said polymer, from said mixture, 
         b2) If said suspension contains thorium, modifying the mixture until the LCST of the polymer in the mixture is reached or exceeded and separating the resulting aggregates from said mixture; and 
         c) Recovering at least one of uranium and/or thorium-free mixture, aggregates bearing uranium and aggregates bearing thorium. 
       
     
     
         2 . The method for separating uranium and thorium from an aqueous suspension according to  claim 1 , comprising
 a) Contacting said suspension with at least two polymers having formula (I),   one polymer having formula (I) wherein R3 and R4 are H and p is an integer which is 1 or more and 10 at the most, said polymer being a flocculating polymer, and   one polymer having formula (I) wherein at least one of R3 and R4 is not H and p is an integer which is 3 or more and 10 at the most, said polymer being a thermosensitive polymer and having a LCST in said suspension,   b 1) Allowing flocculation to occur and separating the aggregates resulting from flocculation of said polymer, from said mixture,   b2) Modifying the mixture until the LCST of the polymer in the mixture is reached or exceeded and separating the resulting aggregates from said mixture; and   c) Recovering the uranium- and thorium-free mixture and/or aggregates bearing uranium and aggregates bearing thorium.   
     
     
         3 . The method according to  claim 1 , wherein said polymer(s) is(are) selected from the group consisting of polymers of formula (I), wherein
 R2 is H or a C1-C6-alkyl, and   R3 and R4 are independently H or a C1-C20-alkyl.   
     
     
         4 . The method according to  claim 1 , wherein said polymer(s) is(are) selected from the group consisting of polymers of formula (I), wherein
 R1 is H,   R2 is H,   R3 and R4 are independently H or CH 2 -CH 3 ,   X and Y are NH, respectively, and   p is 3.   
     
     
         5 . The method according to  claim 1 , wherein in step b2), the LCST of the polymer (I) in said suspension is reached or exceeded by modifying at least one of temperature, pH and ionic strength of said suspension. 
     
     
         6 . The method according to  claim 1 , further comprising separating uranium from aggregates of step b1) and/or separating thorium from aggregates of step b2).